test: add Playwright smoke test for AI note visibility and tab opening

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -73,6 +73,7 @@
     "@types/node": "^24.10.1",
     "@types/react": "^19.2.7",
     "@types/react-dom": "^19.2.3",
+    "@types/ws": "^8.18.1",
     "@vitejs/plugin-react": "^5.1.1",
     "@vitest/coverage-v8": "^4.0.18",
     "esbuild": "^0.27.3",
@@ -86,6 +87,7 @@
     "typescript": "~5.9.3",
     "typescript-eslint": "^8.48.0",
     "vite": "^7.3.1",
-    "vitest": "^4.0.18"
+    "vitest": "^4.0.18",
+    "ws": "^8.19.0"
   }
 }